One type of known mixing system is of the GIFAR type. Such systems consist of a main tube or conduit in which the water circulates, and to which a pipe is joined, the pipe being connected to a tank of liquid cosmetic products, such a liquid soap. A deflector is then situated in the main conduit so as to produce a depression at the level of the joint of the attached pipe, thereby permitting a certain quantity of liquid soap to be drawn in, so as to mix with the water in the main conduit.
This well-known device presents a number of inconveniences, however. In particular, it does not have any closing device to assure that the level of the soap in the tank is water tight, so that the liquid soap may be permitted to enter the pipe of running water even after the faucet has been closed. Furthermore, the flow of the soap is dependent upon several parameters, including the flow of the water in the main tube, the pressure of the water in the pipe, etc. Thus, the flow of soap is rendered practically uncontrollable, and of necessity each device must therefore be adapted to the individual conditions at the time of its installation. Finally, it has been noted that these types of devices large quantities of water are used for a very small quantity of liquid soap.